what do you thing about this
1. create calendar user in database f.e.
public_calendar@domain.com2. Add this account to calendar config file to public calendar variable, add calendar admins to array and eventually define a public calendar category color.
3. users automatically see the public calendar without making tokens or creating feeds. users have it in read only mode, admins in full mode.
and what do you thing about permission to read/write but without deleting? it can be used to add someone else an event in calendar. when that someone else enter the calendar can accept or decline this event.